Comments on: Reducing locking delays in MySQL http://rackerhacker.com/2008/04/16/reducing-locking-delays-in-mysql/ Words of wisdom from a server administrator Mon, 21 May 2012 12:07:17 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: major http://rackerhacker.com/2008/04/16/reducing-locking-delays-in-mysql/#comment-808 major Sat, 03 May 2008 02:19:28 +0000 http://rackerhacker.com/?p=290#comment-808 @jeffatrackaid: I usually specify a tmpdir that isn't /tmp just so I can put temporary tables on an alternate disk. However, you could throw it on a RAM disk for a little extra performance. I've never tried it myself, however. But, if you have the RAM available for that, I'd figure you could configure MySQL to use more memory or you could improve your queries. @jeffatrackaid: I usually specify a tmpdir that isn't /tmp just so I can put temporary tables on an alternate disk. However, you could throw it on a RAM disk for a little extra performance. I've never tried it myself, however. But, if you have the RAM available for that, I'd figure you could configure MySQL to use more memory or you could improve your queries.

]]> By: jeffatrackaid http://rackerhacker.com/2008/04/16/reducing-locking-delays-in-mysql/#comment-806 jeffatrackaid Sat, 03 May 2008 02:10:49 +0000 http://rackerhacker.com/?p=290#comment-806 A major thing I've run into is selects blocking writes due to disk IO. In many cases, I've found selects on BLOB/TEXT columns. These columns cannot be handled with in-memory storage structures so they must be dumped to a tmp table, raising disk IO. If you cannot re-work the SQL not to select these queries, especially with large result sets, then you may want to have mysql use a dedicated disk for tmp tables. With mysql 5.1, you can actually specify many paths to get round-robin load balancing over your disk spindles. http://dev.mysql.com/doc/refman/5.1/en/temporary-files.html I wonder if you used a RAM disk as your tmpdir if that would help? A major thing I've run into is selects blocking writes due to disk IO. In many cases, I've found selects on BLOB/TEXT columns. These columns cannot be handled with in-memory storage structures so they must be dumped to a tmp table, raising disk IO. If you cannot re-work the SQL not to select these queries, especially with large result sets, then you may want to have mysql use a dedicated disk for tmp tables. With mysql 5.1, you can actually specify many paths to get round-robin load balancing over your disk spindles.
http://dev.mysql.com/doc/refman/5.1/en/temporary-files.html

I wonder if you used a RAM disk as your tmpdir if that would help?

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